This is the repository for the Autosave Online extension. It is currently available in the Mozilla Add-on Gallery.
This add-on works by injected a script into every webpage and listening for focus events bubbled up to the document. It saves a reference to the targetted element, and waits for beforeunload to be fired. Then, it collects the values in those elements and saves them locally.
The dist folder contains two subfolders for Mozilla Firefox and Google Chrome. Each of these folders contain code that works in each browser. They are, for the most part, similar, with slight differences due to differences between the browsers.